8.1l Engine Block Drain Plugs

[tjg79]

Are the 8.1L engine block drain plugs on each side of the block different sizes? Whatever the case, what size hex key are they?

 

Also, the service manual calls for using engine drain plug sealant, GM P/N 12346004. What is it? My local dealership part guy indicated that it was just teflon pipe tape. Is that correct?

 

Thanks

[Haulin' 8.1]

Tim the hex sizes are metric. The cheap sets from Autozone will do the trick. The large is a 14mm. The GM part# may be for a brush on teflon paste (like in the plumbing supplies at the hardware store) but that or tape will work just as well.

 

Vernon

[tjg79]

Thanks Vernon

 

So, if I understand what you implied, it's true that the left and right side engine block drain plugs are not the same size?

 

I wasn't sure if I identified the plugs correctly. Also, my left side, large plug, looks more like a 17mm hex bit. I put an 18mm hex on a socket extension up to the plug and it seemed like it was just 1mm too big. The right side is about an 8mm hex bit.

 

I'm not sure if the GM P/N 12346004 is teflon pipe joint paste. My dealership parts guy indicated that the mechanics use teflon tape to seal the engine block plugs. I got the impression that they don't strictly adhear to the service manual instructions.

 

I was reading my service manaul and saw that GM calls out that sealant, GM P/N 12346004, for the cylinder head bolt threads and the valve rocker arm stud threads. I could be wrong, but that doesn't seem like a teflon pipe joint paste job to me.

[Haulin' 8.1]

Tim, I haven't taken the 8.1 plugs out yet but on the other late model GM V8's they are different sizes, one is above the starter and is smaller than the one on the left front. It could be a different size than the small blocks but I doubt it. I know that the shape of the socket confused me also, I chased a 5/8" all over town but it wouldn't fit and ended up being metric.

 

The sealant and where it's called out sounds exactly like teflon pipe paste to me. You don't want coolant seeping past the head studs or oil seeping into the intake ports past the rocker studs. Also you wouldn't want to use thread locker in those locations. I pulled out my Scoggin Dickie catalog and it's listed as so:

 

"GM Teflon Pipe Sealant

Seals machine and tapered threads. Compatable with oil, water, and refrigerant. Ideal for sensor installation (except O2 sensor).

 

Application: For use with all GM vehicles.

 

12346240...GM Teflon Pipe Sealant 50 cc...$18.64"

 

Their web page for it isn't as descriptive. As you can see you pay a lot more for this at the GM parts counter than the hardware store or auto parts. But if you think it's any different go ahead and have the peace of mind. I've been using the hardware grade or autoparts store Permatex brand for years depending on what I find when I run out and have never had a problem related to it. It's just a lot cheaper and bulkier when bought at Home Depot.

[tjg79]

Thanks again Vernon. I checked out the sealant on a couple of websites and it's just as you indicated.

 

Seeing the different size drain plugs had me wondering if they were in fact the drain plugs.

 

Regards

[tjg79]

Well, after looking at an exploded view of the engine block, it appears there are three coolant plugs in the block; two coolant drain plugs located one each side at about the middle of the side, and one coolant hole plug, used in place of the optional Block Heater, located on the left front side. It appears the two coolant drain plugs are the same size and the coolant hole plug is about twice the size of a coolant drain plug.

 

I thought it was odd that the coolant drain plugs would be different sizes. In fact, they are the same size. I was looking at the optional Block Heater hole plug and thought it was the left side engine block coolant drain plug.

[Haulin' 8.1]

Let us know what it ends up Tig, I'm sure it will come up again.

 

Vernon

[luke21]

hi guys. Im new to the site, my name is luke. Im hoping i can get help on here to install my block heater. I bought a zerostart circulating block heatr and i have to hook the inlet side to the "engine block drain hole" and the outlet side the "hose line running from the engine to the passenger compartment heater". Im not sure what im looking for and i want to make sure i get the right engine drain hole and the right hose. any help would be grealy appreciated!

 

Luke

[Riverjet502]

My 502 has one on each side of the block. About in the middle of the block just above the oil pan rail. I use a 1/4 inch brass pipe plug and a few wraps of plain old plumbers teflon tape...